The present invention relates to wireless communication systems. More particularly, and not by way of limitation, the present invention is directed to a system and method for reducing latency between Wideband Code Division Multiplex Access (WCDMA) systems and Enhanced Data GSM Environment (EDGE) systems. EDGE is a wireless Third Generation (3G) technology that allows it to increase data transmission rate and improve data transmission reliability. EDGE can be used for any packet switched application such as an Internet connection. EDGE is implemented as an add-on enhancement to 2G and 2.5G Global System for Mobile Communications (GSM) and General Packet Radio Service (GPRS) networks, making it easier for existing GSM carriers to upgrade to it. Although EDGE requires no hardware or software changes to be made in GSM core networks, base stations must be modified to implement EDGE. EDGE compatible transceiver units must be installed and the base station subsystem (BSS) must be upgraded to support EDGE. New mobile terminal hardware and software are also required to decode/encode the new modulation and coding schemes and carry the higher user data rates to implement new services. However, in the continuing evolution of the 3G standard, WCDMA has been developed. More technically, WCDMA is a wideband spread-spectrum mobile air interface that utilizes the direct sequence Code Division Multiple Access (CDMA) signaling method to achieve higher speeds and support more users compared to the implementation of time division multiplexing (TDMA) used by 2G GSM networks. WCDMA has been developed into a complete set of specifications, a detailed protocol that defines how a mobile phone communicates with the tower, how signals are modulated, how datagrams are structured, and system interfaces are specified allowing free competition on technology elements.
The Third Generation Partnership Project (3GPP) continues to evolve the technology used in wireless communication systems from EDGE to WCDMA. In connection therewith, an objective is to obtain seamless workability between WCDMA and EDGE by reducing latency. This is critical in symmetric service applications such as Voice over IP (VoIP), interactive gaming and push-to-talk over cellular (PoC).
In a conventional system, the mobile station (MS) is capable of indicating to the RAN that it can handle more than 1 time slot (TS) in the uplink, however the RAN is restricted by the current 3GPP standard to assigning only 1TS for an uplink TBF until it finds out about the MS capabilities, either during the second phase of a two phase access or by querying the Serving GPRS Support Node (SGSN) for this information for the case of a one phase access. The result of this is a slower ramp-up in throughput and an increased delay. This restriction increases the initial delay for services like VoIP and Push-to-talk (PoC).
It would be advantageous to have a system and method that reduces latency between WCDMA systems and EDGE systems such that it overcomes the disadvantages of the prior art. The present invention provides such a system and method.